Barack Obama will speak to world leaders on climate change tomorrow during a special UN summit in New York on the eve of the 64th session of the UN general assembly. The nations of the world are working hard to negotiate a new international agreement to combat climate change.

Climate change is one of the greatest challenges facing our world today. Already its impacts are apparent and consequences severe. Arctic sea ice is disappearing faster than expected. The Greenland ice sheet is shrinking. Sea levels threaten to rise higher than previously anticipated. And water supplies are increasingly at risk from both melting glaciers and extreme climate events, such as droughts and floods. These changes threaten not only the environment, but also security and stability. The science sends a simple and stark message: all countries must work together to combat climate change, and the time for action is now.

Obama recognises that the US must be a leader in the global effort to combat climate change. We have a responsibility as the world's largest historic emitter of greenhouse gases. We know that without US emissions reductions no solution to climate change is possible, so the US will take the lead in building a 21st century clean energy economy.

When it comes to climate change, Obama is taking the US in a new direction. The president called on the US Congress to develop comprehensive clean energy legislation to cut emissions 14% from 2005 levels in 2020 and 83% in 2050. A bill has passed the House of Representatives and is making its way through Congress. The president's economic stimulus package includes more than $80bn for clean energy. And recently instituted vehicle standards will increase fuel economy and reduce emissions.

From an environmental perspective, the EU and US climate packages are comparable and lead to emissions reductions that are consistent with the science. Rather than debate on negligible differences between EU and US policies, it is far more critical to work together to prevent unchecked emissions growth among key emerging economies.

To preserve a safe and liveable planet, all major emitting nations have to join together to take strong action. There is no other way to contain climate change – the International Energy Agency estimates 97% of future emissions growth will come from the developing world.

Developed countries need to reduce their emissions substantially by 2020 on an absolute basis, compared to a 2005 or 1990 baseline. Major developing nations must take actions that will substantially reduce their emissions by 2020 on a relative basis, compared to their so-called "business as usual" path. Other developing countries should focus on preparing low-carbon growth plans – with financial and technical assistance where needed – to guide their longer-term development path. It is important to ensure that a new agreement will not require developing countries to take steps that would stifle their capacity to develop and grow.

Ultimately, a climate change agreement must be about not only limiting carbon emissions, but about providing a pathway for sustainable development. Clean energy development is the only sustainable way forward. To facilitate this path, countries with advanced capabilities must stand ready to develop new technologies and assist developing countries in deploying them. If we work together, the effort to build a clean energy global economy can provide significant opportunity, driving investment, economic growth and job creation around the world. This is why we are elevating climate and clean energy to a top-tier issue in key bilateral relationships, including the UK. The US and UK public and private sectors are global leaders in research, development and deployment of new technologies and regulatory approaches that are enabling us to reduce emissions and produce jobs. It is a subject of almost daily discussion with our British counterparts.

The US is clear in its intent to secure a strong international agreement, and I am confident that together we can meet the climate change challenge.